RS_LCD EQU P3.7 ; instruct or data command LCD
RW_LCD EQU P3.0 ; read or write command LCD
CS_LCD EQU P3.1 ; chip select LCD
DATA_BUS EQU P1 ; 8 bit data bus
ORG 0
main: call initialize
mov a,#0 ; set cursor to addr 0
acall goto_lcd
mov dptr,#str1 ; string 1
acall put_str
mov a,#40h ; set curser to addr 40h
acall goto_lcd
mov dptr,#str2 ; string 2
acall put_str
sjmp $
initialize: call init_lcd ; Initial LCD
ret
;initialize character LCD ,5*7 dot,4 line
init_lcd: mov a,#15 ; delay 15 ms when power on
acall delay_ms
mov a,#38h ; function set
acall write_ins_lcd
mov a,#5 ; delay 5 ms when power on
acall delay_ms
mov a,#38h ; function set
acall write_ins_lcd
mov a,#1 ; delay 1 ms when power on
acall delay_ms
mov a,#38h ; function set
acall write_ins_lcd
acall busy_lcd
mov a,#38h ; function set
acall write_ins_lcd
acall busy_lcd
mov a,#0ch ; display on/off
acall write_ins_lcd
acall busy_lcd
mov a,#06h ; entry mode set
acall write_ins_lcd
acall busy_lcd
acall clr_lcd ; clr display
ret
; Write ADCII to LCD the value in the accumulator.
write_lcd: push acc
setb RS_LCD ; data reg. (DR)
clr RW_LCD ; write data
setb CS_LCD ; enable strobe
mov DATA_BUS,acc ; write data
clr CS_LCD ; disable LCD
acall delay_40us ; wait for excution time 40 uS
acall busy_lcd ; chack busy
pop acc
ret
; Read busy flag LCD
busy_lcd: clr RS_LCD ; instruction reg. (IR)
setb RW_LCD ; read data
setb CS_LCD ; eanble strobe
wait_bl: mov a,#0ffh ; clear data bus
mov a,DATA_BUS ; read command
jb acc.7,wait_bl ; wait BF flag is clr
clr CS_LCD ; disable LCD
ret
; clear display and set DD ram address 0
clr_lcd: mov a,#1 ; clear command
acall write_ins_lcd ; write instruct
mov a,#2 ; delay 2 mS
acall delay_ms
acall busy_lcd ; chack busy
ret
; cursor on
cur_on: mov a,#00fh ; D=1, C=1, B=1;
acall write_ins_lcd ; write instruct
mov a,#2 ; delay 2 mS
acall delay_ms
acall busy_lcd ; check busy
ret
; cursor on
cur_off: mov a,#00ch ; D=1, C=1, B=1;
acall write_ins_lcd ; write instruct
mov a,#2 ; delay 2 mS
acall delay_ms
acall busy_lcd ; check busy
ret
; set DD ram address 0
return_home_lcd:mov a,#2 ; return home command
acall write_ins_lcd ; write instruct
mov a,#2 ; delay 2 mS
acall delay_ms
acall busy_lcd ; check busy
ret
; set DD ram address the value in the accumulator.
goto_lcd: setb acc.7 ; set DD ram command
acall write_ins_lcd ; write instruct
acall delay_40us ; wait for excution time 40 uS
acall busy_lcd ; check busy
ret
write_ins_lcd: clr RS_LCD ; instruction reg. (IR)
clr RW_LCD ; write data
setb CS_LCD ; eanble strobe
mov DATA_BUS,acc ; write commnad
clr CS_LCD ; disable LCD
ret
; Delay for one mS times the value in the accumulator. X'TAL 12 MHz
delay_ms: push acc ; 2 uS
push b ; 2 uS
mov b,#241 ; 2 uS
dm: djnz b,$ ; 2 uS ,248 * 2 = 496
mov b,#249 ; 2 uS
djnz b,$ ; 2 uS ,249 * 2 = 498
mov b,#248 ; 2 uS
djnz acc,dm ; 2 uS
pop b ; 2 uS
pop acc ; 2 uS
ret ; 2 uS
; Delay for 40 uS timers the value in the accumulator. X'TAL 12 MHz
delay_40us: push acc ; 2 uS
mov a,#15 ; 2 uS
djnz acc,$ ; 2 uS ,15 * 2 = 30
pop acc ; 2 uS
ret ; 2 uS
; Write LCD in program momory
; Input dptr = data pointer
put_str: acall goto_lcd
put_str1: clr a ; clear accumulator
movc a,@a+dptr ; get charecter into accumulator
jz end_put_str ; jump if charecter is end of file (00h)
acall write_lcd ; put charecter to LCD
inc dptr
sjmp put_str1 ; next charecter
end_put_str: inc dptr
ret
str1: DB "* Test LCD *",0
str2: DB "dh_servis",0
END
